linux-kernel - [RFC 0/3] Introduce infrastructure to report time in deepest state

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Date:   Mon, 31 Oct 2022 15:43:16 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Sven van Ashbrook <svenva@...omium.org>,
        Rafael J Wysocki <rafael@...nel.org>,
        <platform-driver-x86@...r.kernel.org>, <linux-pm@...r.kernel.org>
CC:     Rajneesh Bhardwaj <irenic.rajneesh@...il.com>,
        S-k Shyam-sundar <Shyam-sundar.S-k@....com>,
        <rrangel@...omium.org>, Rajat Jain <rajatja@...gle.com>,
        David E Box <david.e.box@...el.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mario Limonciello <mario.limonciello@....com>,
        <linux-kernel@...r.kernel.org>
Subject: [RFC 0/3] Introduce infrastructure to report time in deepest state

Sven van Ashbrook brought a patch to the kernel mailing list that
attempted to change the reporting level of a s0ix entry issue to a
different debugging level so that infastructure used by Google could
better scan logs to catch problems.

This approach was rejected, but during the conversation another
suggestion was made by David E. Box to introduce some infrastructure
into the kernel to report this information.

As it's information that is reported by both AMD and Intel platforms
over s2idle, this seems to make sense.

This series introduces a new sysfs file, a symbol for kernel modules to
use to populate it and changes to both AMD and Intel drivers to utilize
it.

The expectation is that userspace could read this file after s2idle
occurred to infer how much of the s2idle cycle was spent in the deepest
hardware state.

Mario Limonciello (3):
  PM: Add a sysfs file to represent whether hardware reached the deepest
    state
  platform/x86/amd: pmc: Report duration of time in deepest hw state
  platform/x86/intel/pmc: core: Report duration of time in deepest HW
    state

 Documentation/ABI/testing/sysfs-power |  8 ++++++++
 drivers/platform/x86/amd/pmc.c        |  4 +---
 drivers/platform/x86/intel/pmc/core.c |  2 ++
 include/linux/suspend.h               |  2 ++
 kernel/power/main.c                   | 14 ++++++++++++++
 5 files changed, 27 insertions(+), 3 deletions(-)

-- 
2.34.1